I want to avoid mixing ImageMagick commands in with the MagickWand API (Plus I can't do exec commands on my web server). I know I can roll my own, but I am sure having the caption: functionality built into the code would be far faster than anything I can write in PHP to do this.. Are there any plans to add it in to a future release?

We have no plans to add word wrapping to ImageMagick other than the caption: format which performs a rudimentary word wrapping, see http://www.imagemagick.org/Usage/text/#caption. Note, you can access the caption: format directly with MagickReadImage().